US4693825A - Method for the preparation of polybenzimidazole membranes - Google Patents
Method for the preparation of polybenzimidazole membranes Download PDFInfo
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- US4693825A US4693825A US06/779,017 US77901785A US4693825A US 4693825 A US4693825 A US 4693825A US 77901785 A US77901785 A US 77901785A US 4693825 A US4693825 A US 4693825A
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- polybenzimidazole
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- polymer
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- 239000012528 membrane Substances 0.000 title claims abstract description 71
- 229920002480 polybenzimidazole Polymers 0.000 title claims abstract description 62
- 239000004693 Polybenzimidazole Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- WVDDGKGOMKODPV-UHFFFAOYSA-N Benzyl alcohol Chemical compound OCC1=CC=CC=C1 WVDDGKGOMKODPV-UHFFFAOYSA-N 0.000 claims abstract description 57
- 235000019445 benzyl alcohol Nutrition 0.000 claims abstract description 19
- 239000002904 solvent Substances 0.000 claims description 44
- 229920000642 polymer Polymers 0.000 claims description 43
- 125000003118 aryl group Chemical group 0.000 claims description 19
- 230000001112 coagulating effect Effects 0.000 claims description 11
- 239000007787 solid Substances 0.000 claims description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 7
- 125000004432 carbon atom Chemical group C* 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- YLQBMQCUIZJEEH-UHFFFAOYSA-N Furan Chemical compound C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical group CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 6
- KYQCOXFCLRTKLS-UHFFFAOYSA-N Pyrazine Chemical compound C1=CN=CC=N1 KYQCOXFCLRTKLS-UHFFFAOYSA-N 0.000 claims description 6
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 6
- SMWDFEZZVXVKRB-UHFFFAOYSA-N Quinoline Chemical compound N1=CC=CC2=CC=CC=C21 SMWDFEZZVXVKRB-UHFFFAOYSA-N 0.000 claims description 6
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical compound C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 claims description 6
- 238000000151 deposition Methods 0.000 claims description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- 125000003785 benzimidazolyl group Chemical group N1=C(NC2=C1C=CC=C2)* 0.000 claims description 4
- 125000000623 heterocyclic group Chemical group 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 125000004433 nitrogen atom Chemical group N* 0.000 claims description 4
- MGADZUXDNSDTHW-UHFFFAOYSA-N 2H-pyran Chemical compound C1OC=CC=C1 MGADZUXDNSDTHW-UHFFFAOYSA-N 0.000 claims description 3
- PCNDJXKNXGMECE-UHFFFAOYSA-N Phenazine Natural products C1=CC=CC2=NC3=CC=CC=C3N=C21 PCNDJXKNXGMECE-UHFFFAOYSA-N 0.000 claims description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 3
- 229930192474 thiophene Natural products 0.000 claims description 3
- 125000002947 alkylene group Chemical group 0.000 claims description 2
- 239000013557 residual solvent Substances 0.000 claims 2
- 238000005266 casting Methods 0.000 abstract description 11
- 238000000137 annealing Methods 0.000 abstract description 10
- 238000001223 reverse osmosis Methods 0.000 abstract description 10
- 239000000243 solution Substances 0.000 description 31
- 230000004907 flux Effects 0.000 description 11
- 239000010410 layer Substances 0.000 description 10
- 150000003839 salts Chemical class 0.000 description 10
- HYZJCKYKOHLVJF-UHFFFAOYSA-N 1H-benzimidazole Chemical compound C1=CC=C2NC=NC2=C1 HYZJCKYKOHLVJF-UHFFFAOYSA-N 0.000 description 6
- KWGKDLIKAYFUFQ-UHFFFAOYSA-M lithium chloride Chemical compound [Li+].[Cl-] KWGKDLIKAYFUFQ-UHFFFAOYSA-M 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- -1 bisulfite ions Chemical class 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- 125000001424 substituent group Chemical group 0.000 description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000004305 biphenyl Substances 0.000 description 2
- 235000010290 biphenyl Nutrition 0.000 description 2
- 229920002301 cellulose acetate Polymers 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000593 degrading effect Effects 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 235000019253 formic acid Nutrition 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- ZUOUZKKEUPVFJK-UHFFFAOYSA-N phenylbenzene Natural products C1=CC=CC=C1C1=CC=CC=C1 ZUOUZKKEUPVFJK-UHFFFAOYSA-N 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 238000000108 ultra-filtration Methods 0.000 description 2
- HIXDQWDOVZUNNA-UHFFFAOYSA-N 2-(3,4-dimethoxyphenyl)-5-hydroxy-7-methoxychromen-4-one Chemical compound C=1C(OC)=CC(O)=C(C(C=2)=O)C=1OC=2C1=CC=C(OC)C(OC)=C1 HIXDQWDOVZUNNA-UHFFFAOYSA-N 0.000 description 1
- KSSJBGNOJJETTC-UHFFFAOYSA-N COC1=C(C=CC=C1)N(C1=CC=2C3(C4=CC(=CC=C4C=2C=C1)N(C1=CC=C(C=C1)OC)C1=C(C=CC=C1)OC)C1=CC(=CC=C1C=1C=CC(=CC=13)N(C1=CC=C(C=C1)OC)C1=C(C=CC=C1)OC)N(C1=CC=C(C=C1)OC)C1=C(C=CC=C1)OC)C1=CC=C(C=C1)OC Chemical compound COC1=C(C=CC=C1)N(C1=CC=2C3(C4=CC(=CC=C4C=2C=C1)N(C1=CC=C(C=C1)OC)C1=C(C=CC=C1)OC)C1=CC(=CC=C1C=1C=CC(=CC=13)N(C1=CC=C(C=C1)OC)C1=C(C=CC=C1)OC)N(C1=CC=C(C=C1)OC)C1=C(C=CC=C1)OC)C1=CC=C(C=C1)OC KSSJBGNOJJETTC-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 229910003556 H2 SO4 Inorganic materials 0.000 description 1
- 101100386054 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) CYS3 gene Proteins 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 150000008064 anhydrides Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 239000003637 basic solution Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 229920001727 cellulose butyrate Polymers 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010612 desalination reaction Methods 0.000 description 1
- 229940113088 dimethylacetamide Drugs 0.000 description 1
- 238000000578 dry spinning Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000909 electrodialysis Methods 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 125000000816 ethylene group Chemical group [H]C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000005580 one pot reaction Methods 0.000 description 1
- PRHCPIGZWZUJAR-UHFFFAOYSA-N phenyl 3,4-diaminobenzoate Chemical compound C1=C(N)C(N)=CC=C1C(=O)OC1=CC=CC=C1 PRHCPIGZWZUJAR-UHFFFAOYSA-N 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920000867 polyelectrolyte Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 239000001044 red dye Substances 0.000 description 1
- 239000004627 regenerated cellulose Substances 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000011877 solvent mixture Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 101150035983 str1 gene Proteins 0.000 description 1
- 150000003457 sulfones Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0011—Casting solutions therefor
- B01D67/00111—Polymer pretreatment in the casting solutions
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0013—Casting processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0002—Organic membrane manufacture
- B01D67/0009—Organic membrane manufacture by phase separation, sol-gel transition, evaporation or solvent quenching
- B01D67/0016—Coagulation
- B01D67/00165—Composition of the coagulation baths
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0039—Inorganic membrane manufacture
- B01D67/0069—Inorganic membrane manufacture by deposition from the liquid phase, e.g. electrochemical deposition
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/06—Organic material
- B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
- B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2323/00—Details relating to membrane preparation
- B01D2323/12—Specific ratios of components used
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
Definitions
- This invention relates to a process for preparing membranes. More particularly, the invention relates to an improved process for the production of polybenzimidazole membranes which may be used, for example, in reverse osmosis.
- Semipermeable membranes proposed in the past have been formed from a variety of materials, and are characterized by the ability to permit one component (e.g., ions or molecules) of a solution to pass through the membrane to the substantial exclusion of other components (e.g., other ions or molecules).
- components e.g., ions or molecules
- Examples of substances heretofore recognized to possess this property include cellophane (i.e., regenerated cellulose), cellulose esters (e.g., cellulose acetate, cellulose butyrate, etc.), animal or protein membranes, polyelectrolyte complexes, ethyl cellulose, cross-linked polyacrylates, etc.
- the semipermeable membranes of the prior art are of limited applicability in many separatory processes, such as reverse osmosis or ultrafiltration because of the inherent disadvantages relating to their chemical stability, strength, thermal stability, efficiency, length of life, and cost.
- the prior art membranes exhibit low thermal stability and, therefore, cannot be used successfully under conditions wherein the liquid undergoing treatment is at an elevated temperature. This may be a decided disadvantage in situations where the components to be separated only exist in solution at higher temperatures, or when it is economically advantageous to separate components of a solution at elevated temperatures rather than going to the expense of cooling it.
- some membranes exhibit a decided decrease in efficiency upon an increase in temperature or pressure thereby limiting their range of applicability. Solvent susceptibility may be another factor affecting the use of a particular porous membrane in a separation process. Additionally, semipermeable membranes may be inappropriate for a particular application due to low solute rejection values or low flux.
- membranes comprised of polybenzimidazole polymers have been developed. See, for example, U.S. Pat. Nos. 3,699,038, 3,720,607, 3,737,042, 3,841,492, 3,851,025, 4,020,142, 4,448,687 and 4,512,894. In some instances, these membranes are fragile and contained voids in the membrane structure that reduced their strength.
- U.S. Pat. Nos. 3,699,038, 3,737,042, 3,841,492, 3,851,025, 4,448,687, and 4,512,894 all disclose processes for the preparation of polybenzimidazole semipermeable membranes that include an annealing step.
- the annealing step is added to the membrane preparation process to improve the mechanical properties of those membranes.
- the annealing step increases the cost and the time required to produce semipermeable membranes.
- annealing enhances the salt rejection properties of membranes, it has the undesirable effect of decreasing the flux of the membrane.
- U.S. Pat. No. 3,642,720 discloses the preparation of polybenzimidazole films without employing an annealing step. However, it does not disclose the preparation of membranes or the use of a non-solvent in the casting solution to enhance the mechanical properties of films.
- the present invention constitutes an improved process for producing a semipermeable polybenzimidazole membrane which comprises the following steps:
- the polymeric material used to form the semipermeable membranes of the present invention is a linear polybenzimidazole.
- Polybenzimidazoles are a known class of heterocyclic polymers. Typical polymers of this class and their preparation are more fully described in U.S. Pat. Nos. 2,895,948, Re. 26,065, and in the Journal of Polymer Science, Vol. 50, pages 511-539 (1961) which are herein incorporated by reference.
- the polybenzimidazoles consist essentially of recurring units of the following Formulas I and II.
- Formula I is: ##STR1## wherein R is a tetravalent aromatic nucleus, preferably symmetrically substituted, with the nitrogen atoms forming the benzimidazole rings being paired upon adjacent carbon atoms, i.e., ortho carbon atoms, of the aromatic nucleus, and R' is a member of the class consisting of (1) an aromatic ring, (2) an alkylene group (preferably those having 4 to 8 carbon atoms), and (3) a heterocyclic ring from the class consisting of (a) pyridine, (b) pyrazine, (c) furan, (d) quinoline, (e) thiophene, and (f) pyran.
- Formula II is: ##STR2## wherein Z is an aromatic nucleus having the nitrogen atoms forming the benzimidazole ring paired upon adjacent carbon atoms of the aromatic nucleus.
- aromatic polybenzimidazoles are selected from polymers consisting essentially of the recurring units of Formula I wherein R' is an aromatic ring or a heterocyclic ring and Formula II.
- the aromatic polybenzimidazoles having the recurring units of Formula II may be prepared by self-condensing a trifunctional aromatic compound containing only a single set of ortho disposed diamino substituents and an aromatic, preferably phenyl, carboxylate ester substituent.
- exemplary of polymers of this type is poly-2,5(6)-benzimidazole prepared by the autocondensation of phenyl-3,4-diaminobenzoate.
- the aromatic polybenzimidazoles having the recurring units of Formula I may be prepared by condensing an aromatic tetraamine compound containing a pair of orthodiamino substituents on the aromatic nucleus with a dicarboxylic compound selected from the class consisting of (a) the diphenyl ester of an aromatic dicarboxylic acid, (b) the diphenyl ester of a heteroyclic dicarboxylic acid wherein the carboxyl groups are substituents upon a carbon in a ring compound selected from the class consisting of pyridine, pyrazine, furan, quinoline, thiophene and pyran and (c) an anhydride of an aromatic dicarboxylic acid.
- a dicarboxylic compound selected from the class consisting of (a) the diphenyl ester of an aromatic dicarboxylic acid, (b) the diphenyl ester of a heteroyclic dicarboxylic acid wherein the carboxyl groups are substituents
- polybenzimidazoles which have the recurring structure of Formula I are as follows:
- the preferred polybenzimidazole for use in the present process is one prepared from poly-2,2'-(m-phenylene)-5,5,'bibenzimidazole, the recurring unit of which is: ##STR3##
- any polymerization process known to those skilled in the art may be employed to prepare the polybenzimidazoles which may then be formed into a semipermeable membrane according to the process of this invention.
- Representative techniques for preparing the polybenzimidazole are disclosed in U.S. Pat. Nos. 3,509,108, 3,549,603, 3,551,389, 4,312,976, 4,452,971, 4,452,972, 4,483,977 and 4,485,232 which are herein incorporated by reference.
- equimolar quantities of the monomeric tetraamine and dicarboxyl compound are introduced into a first stage melt polymerization reaction zone and heated at a temperature above about 200° C., preferably at least about 250° C., and more preferably from about 270° C. to 300° C.
- the reaction is conducted in a substantially oxygen-free atmosphere, i.e., below about 20 ppm oxygen and preferably below about 8 ppm oxygen, until a foamed prepolymer is formed having an inherent viscosity, expressed as deciliters per gram, of at least 0.1 and preferably from about 0.13 to 0.3.
- the inherent viscosity (I.V.) as used herein is determined from a solution of 0.4 grams of the polymer in 100 ml. of 97 percent H 2 SO 4 at 25° C.
- the foamed prepolymer is cooled and then powdered or pulverized in any convenient manner.
- the resulting prepolymer powder is then introduced into a second stage polymerization reaction zone wherein it is heated under substantially oxygen-free conditions, as described above, to yield a polybenzimidazole polymer product, desirably having an I.V., as measured above, of at least 0.4, e.g., 0.8 to 1.1 or more.
- the temperature employed in the second stage is at least 250° C., preferably at Least 325° C., and more preferably from about 350° C. to 425° C.
- the second stage reaction generally takes at least 0.5 hour, and preferably from about 1 to 4 hours or more. It is, of course, also possible to prepare the instant polymers via a one-step reaction. However, the previously-described two-step process is preferred.
- the solvents utilized to form the polybenzimidazole polymer casting solutions from which semipermeable membranes are cast include those solvents which are commonly recognized as being capable of dissolving the particular polybenzimidazole polymer.
- the solvents may be selected from those commonly utilized in the formation of polybenzimidazole dry spinning solutions.
- suitable solvents include N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone.
- the particularly preferred solvent is N,N-dimethyl acetamide.
- Additional representative solvents include formic acid, acetic acid, and sulfuric acid.
- the polymer casting solutions may be prepared first by dissolving polybenzimidazole in a solvent.
- the amount of polybenzimidazole which is dissolved in the solvent should be enough so that the casting solution containing a polymer, a solvent and a non-solvent will contain from about 5 to 30 percent by weight of the polymer based on the total weight of the solution, and preferably from about 10 to 20 percent by weight, with about 15 percent being most preferred.
- the quantity of polybenzimidazole dissolved in the solvent should be such that the casting solution has a viscosity of about 50 to 4,000 poise at 30° C., and preferably about 400 to 600 poise.
- One suitable means for dissolving the polymer in the solvent is by mixing the materials at a temperature above the normal boiling point of the solvent, for example, about 25° C. to 120° C. above such boiling point, and at a pressure of 2 to 15 atmospheres for a period of 1 to 5 hours.
- the resulting solutions are preferably filtered to remove any undissolved polymer.
- a minor amount of lithium chloride optionally may be provided in the solution in accordance with the teachings of commonly-assigned U.S. Pat. No. 3,502,606.
- the lithium chloride serves to prevent the polybenzimidazole polymer from phasing out of the solution upon standing for extended periods of time.
- benzyl alcohol is added to the polymeric casting solution.
- the benzyl alcohol is added at about the 5 to 35 percent by weight level, preferably the 10 to 25 percent by weight level, based upon the total weight of the polymeric solution.
- the maximum solubility of benzyl alcohol in the polymeric solution is about 35 percent by weight based upon the total weight of the polymeric solution containing the polymer, benzyl alcohol and the solvent.
- the amount of benzyl alcohol added will depend on the desired combination of the flux rate and the salt rejection rate. When benzyl alcohol is added at about its maximum solubility level (i.e. about 35 percent by weight), the highest combination of high flux, high salt rejection rates is obtained. Decreasing the amount of benzyl alcohol will decrease the flux and increase the salt rejection properties of the resulting membrane.
- the casting solution of polybenzimidazole polymer in the present process is deposited upon a support to form a wet film of the same.
- the nature of the support is not critical and may be selected from a variety of materials including ceramic, glass, or metallic plates (e.g., stainless steel).
- the support is preferably provided with retaining elements, or raised edges, whereby the solution is confined to the surface thereof at the desired location until its consistency is such that retaining elements are no longer needed. Numerous techniques are available for the application of the solution to the support as will be apparent to those skilled in the art. For instance, the polybenzimidazole polymer solution may be simply poured upon a level support in a quantity sufficient for it to assume the desired uniform thickness. A blade is then drawn over the surface of the wet film to aid the deposition of a wet film of uniform thickness.
- the thickness of the wet film deposited upon the support is influenced by the desired thickness of the polybenzimidazole semipermeable membrane ultimately to be produced.
- the wet film is deposited upon the support in a substantially uniform thickness of about 0.5 to 30.0 mils and preferably 1.0 to 10.0 mils. In a particularly preferred embodiment of the invention, the wet film is deposited in a thickness of about 1.0 to 5.0 mils.
- a quantity of solvent is next evaporated from the exposed surface of the wet film to allow the formation of a relatively thin solid layer (i.e., a thin porous polymeric film) on the exposed surface of the film.
- the thin solid layer commonly exhibits a thickness of about 0.01 to 20 microns and preferably about 1 to 10 microns.
- the solvent present near the surface of the wet film is flashed off and a thin coagulated solid layer or skin of polybenzimidazole polymer remains.
- the evaporation of solvent from the exposed surface of the wet film may be accomplished by a variety of techniques as will be apparent to those skilled in the art. For instance, a stream of air or other gas at ambient or at an elevated temperature (e.g. approaching the boiling point of the solvent) may simply be directed at the exposed surface of the wet film. Other methods of evaporation are listed in U.S. Pat. No. 4,512,894.
- the time required to form the desired thin solid layer upon the exposed surface of the wet film commonly ranges from about 5 seconds to 30 minutes, and preferably from about 15 seconds to 5 minutes.
- the temperature at which the solvent is removed is generally room temperature, although higher temperatures may also be employed.
- the resulting film, bearing a thin solid layer upon its surface, is next converted to a semipermeable membrane by coagulating the film in a medium which is a non-solvent for the polybenzimidazole polymer and which is capable of removing residual quantities of the polybenzimidazole solvent.
- the non-solvent is aqueous in nature and most preferably it is water.
- the coagulating step the remaining polybenzimidazole polymer within the wet film is coagulated while the solvent which originally dissolved the polymer is removed.
- the coagulating step is preferably carried out by immersing the film in the liquid medium.
- a water medium is provided at a relatively cool temperature, for example, at about 5° C. to 30° C., and at a temperature of about 10° C. to 25° C. in a particularly preferred embodiment. Satisfactory coagulation times commonly range from about 20 seconds to 20 minutes, and preferably from about 2 to 5 minutes.
- the resulting flat film membrane formed of the polybenzimidazole consists of an outer, relatively thin, surface layer formed during the evaporation step adjacent to a relatively thick layer of a more porous structure.
- the membranes are characterized by high thermal stability and can withstand temperatures during use in excess of 125° C. Also, the membranes exhibit a high degree of chemical stability, and can continue to function in spite of contact with a wide variety of reagents and solvents.
- the polybenzimidazole membranes have high flux and salt rejection properties. The flux of the membranes is between 21 and 25 gfd, and the salt rejection rate is between 89 and 93 percent when measured at 400 psi. using a 0.2 percent salt solution.
- the process of the present invention By employing the process of the present invention, high flux, high salt rejection membranes may be produced. Without the annealing step of the prior art, reverse osmosis membranes can be produced inexpensively. As compared to annealed membranes, the unannealed membranes of the present invention have few or no voids in the membrane structure. Consequently, the mechanical strength of the membranes is enhanced.
- the polybenzimidazole membranes of the present invention once positioned upon a conventional porous support, such as a porous steel plate, may be utilized to separate components of a solution by a variety of techniques, such as reverse osmosis, electrodialysis or ultrafiltration.
- the polybenzimidazole membranes of the present invention are particularly suited for use in desalination operations utilizing reverse osmosis.
- a casting dope was prepared containing 15.0 percent by weight of a polybenzimidazole polymer (poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole) having a inherent viscosity of 0.9, 2.0 percent by weight lithium chloride, 28.6 percent by weight benzyl alcohol and 54.4 percent by weight of dimethylacetamide.
- a 1.0 mil wet film was cast from the dope on a non-woven polyester fabric marketed by Eaton-Dikeman under the trademark Hollytex. The fabric was placed on a moving conveyor belt and a thin surface layer was formed on the wet film by heating the film to about 50° C.
- the membrane was maintained on the conveyor belt in the oven for 30 seconds. The membrane was then coagulated for 16 minutes in water maintained at 10° C. and then rolled up and stored in water. The resulting membrane exhibited a film thickness of about 1.0 mils, a flux of 24.5 gfd., a salt rejection percent of 93.1 and a red dye passage rate of 0 to 0.2 ppm.
- the above rates were measured in an Osmonics, Inc. flow loop maintained at 25° C., and 400 psi, employing an aqueous solution containing 0.2 percent by weight sodium chloride, and 100 ppm Red Dye #40.
- the addition of benzyl alcohol in the membrane casting solution permits high flux, high salt rejection membranes to be produced without an annealing step.
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Abstract
Description
Claims (17)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US06/779,017 US4693825A (en) | 1985-09-23 | 1985-09-23 | Method for the preparation of polybenzimidazole membranes |
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US06/779,017 US4693825A (en) | 1985-09-23 | 1985-09-23 | Method for the preparation of polybenzimidazole membranes |
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US4693825A true US4693825A (en) | 1987-09-15 |
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US06/779,017 Expired - Fee Related US4693825A (en) | 1985-09-23 | 1985-09-23 | Method for the preparation of polybenzimidazole membranes |
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Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4828699A (en) * | 1987-08-20 | 1989-05-09 | Hoechst Celanese Corporation | Process for the production of microporous polybenzimidazole articles |
US4842740A (en) * | 1988-08-05 | 1989-06-27 | Hoechst Celanese Corporation | Membranes prepared from blend of polybenzimidazole with polyarylates |
US4902422A (en) * | 1988-12-06 | 1990-02-20 | Board Regents The University Of Texas System | Defect-free ultrahigh flux asymmetric membranes |
US5114579A (en) * | 1990-10-22 | 1992-05-19 | The United States Of America As Represented By The United States Department Of Energy | Separation of metals by supported liquid membrane |
US6623639B2 (en) | 1999-03-19 | 2003-09-23 | Bend Research, Inc. | Solvent-resistant microporous polybenzimidazole membranes |
US20040031393A1 (en) * | 2000-09-05 | 2004-02-19 | De Bruin Wilhelmus Johannes | Apparatus for preparing a coffee extract with a fine-bubble froth layer using a rough impact surface |
US20040118773A1 (en) * | 2001-03-07 | 2004-06-24 | Oemer Uensal | Method for producing a membrane made of bridged polymer and a fuel cell |
US20040262227A1 (en) * | 2001-06-19 | 2004-12-30 | Joachim Kiefer | Polyazole-based polymer films |
US20050272859A1 (en) * | 2004-06-07 | 2005-12-08 | Klaehn John R | Polybenzimidazole compounds, polymeric media, and methods of post-polymerization modifications |
US20050272880A1 (en) * | 2004-06-07 | 2005-12-08 | Bechtel Bwxt Idaho, Llc | Polybenzimidazole compounds, polymeric media, and methods of post-polymerization modifications |
US20060079392A1 (en) * | 2002-10-04 | 2006-04-13 | Pemeas Gmbh | Proton-conducting polymer membrane that contains polyazoles and is coated with a catalyst layer, and application thereof in fuel cells |
WO2012010886A1 (en) | 2010-07-19 | 2012-01-26 | Imperial Innovations Limited | Asymmetric membranes for use in nanofiltration |
US20230024915A1 (en) * | 2021-07-16 | 2023-01-26 | Battelle Memorial Institute | Porous Polybenzimidazole Membrane Supports for Composite Membranes |
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US3720607A (en) * | 1970-04-15 | 1973-03-13 | Celanese Corp | Reverse osmosis process employing polybenzimidazole membranes |
US3841492A (en) * | 1972-01-19 | 1974-10-15 | Celanese Corp | Production of semipermeable polybenzimidazole membranes |
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Patent Citations (2)
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US3720607A (en) * | 1970-04-15 | 1973-03-13 | Celanese Corp | Reverse osmosis process employing polybenzimidazole membranes |
US3841492A (en) * | 1972-01-19 | 1974-10-15 | Celanese Corp | Production of semipermeable polybenzimidazole membranes |
Cited By (29)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4828699A (en) * | 1987-08-20 | 1989-05-09 | Hoechst Celanese Corporation | Process for the production of microporous polybenzimidazole articles |
US4842740A (en) * | 1988-08-05 | 1989-06-27 | Hoechst Celanese Corporation | Membranes prepared from blend of polybenzimidazole with polyarylates |
EP0354040A2 (en) * | 1988-08-05 | 1990-02-07 | Hoechst Celanese Corporation | Membranes prepared from blends of polybenzimidazole with polyarylates |
EP0354040A3 (en) * | 1988-08-05 | 1990-10-17 | Hoechst Celanese Corporation | Membranes prepared from blends of polybenzimidazole with polyarylates |
US4902422A (en) * | 1988-12-06 | 1990-02-20 | Board Regents The University Of Texas System | Defect-free ultrahigh flux asymmetric membranes |
US5114579A (en) * | 1990-10-22 | 1992-05-19 | The United States Of America As Represented By The United States Department Of Energy | Separation of metals by supported liquid membrane |
US6623639B2 (en) | 1999-03-19 | 2003-09-23 | Bend Research, Inc. | Solvent-resistant microporous polybenzimidazole membranes |
US20040084365A1 (en) * | 1999-03-19 | 2004-05-06 | Barss Robert P. | Solvent-resistant microporous polybenzimidazole membranes and modules |
US6986844B2 (en) | 1999-03-19 | 2006-01-17 | Bend Research, Inc. | Solvent-resistant microporous polybenzimidazole membranes and modules |
US20040031393A1 (en) * | 2000-09-05 | 2004-02-19 | De Bruin Wilhelmus Johannes | Apparatus for preparing a coffee extract with a fine-bubble froth layer using a rough impact surface |
US20040118773A1 (en) * | 2001-03-07 | 2004-06-24 | Oemer Uensal | Method for producing a membrane made of bridged polymer and a fuel cell |
US7229553B2 (en) * | 2001-03-07 | 2007-06-12 | Pemeas Gmbh | Method for producing a membrane made of bridged polymer and a fuel cell |
US20040262227A1 (en) * | 2001-06-19 | 2004-12-30 | Joachim Kiefer | Polyazole-based polymer films |
US7485227B2 (en) | 2001-06-19 | 2009-02-03 | Basf Fuel Cell Gmbh | Polyazole-based polymer films |
US20060079392A1 (en) * | 2002-10-04 | 2006-04-13 | Pemeas Gmbh | Proton-conducting polymer membrane that contains polyazoles and is coated with a catalyst layer, and application thereof in fuel cells |
US7661542B2 (en) * | 2002-10-04 | 2010-02-16 | Basf Fuel Cell Gmbh | Proton-conducting polymer membrane that contains polyazoles and is coated with a catalyst layer, and application therof in fuel cells |
US7632898B2 (en) | 2004-06-07 | 2009-12-15 | Battelle Energy Alliance, Llc | Polymeric media comprising polybenzimidazoles N-substituted with organic-inorganic hybrid moiety |
US7309758B2 (en) | 2004-06-07 | 2007-12-18 | Battelle Energy Alliance, Llc | Polybenzimidazole compounds, polymeric media, and methods of post-polymerization modifications |
US20090012253A1 (en) * | 2004-06-07 | 2009-01-08 | Klaehn John R | Polybenzimidazole compounds |
US20090012190A1 (en) * | 2004-06-07 | 2009-01-08 | Klaehn John R | Polymeric Media Comprising Polybenzimidazoles N-substituted with Organic-Inorganic Hybrid Moiety |
US20050272859A1 (en) * | 2004-06-07 | 2005-12-08 | Klaehn John R | Polybenzimidazole compounds, polymeric media, and methods of post-polymerization modifications |
US20050272880A1 (en) * | 2004-06-07 | 2005-12-08 | Bechtel Bwxt Idaho, Llc | Polybenzimidazole compounds, polymeric media, and methods of post-polymerization modifications |
US7259230B2 (en) | 2004-06-07 | 2007-08-21 | Battelle Energy Alliance, Llc | Polybenzimidazole compounds, polymeric media, and methods of post-polymerization modifications |
US7772361B2 (en) | 2004-06-07 | 2010-08-10 | Battelle Energy Alliance, Llc | Polybenzimidazole compounds |
US8063174B2 (en) | 2004-06-07 | 2011-11-22 | Battelle Energy Alliance, Llc | Polybenzimidazole compounds |
US8129498B2 (en) | 2004-06-07 | 2012-03-06 | Battelle Energy Alliance, Llc | Polymeric medium |
WO2012010886A1 (en) | 2010-07-19 | 2012-01-26 | Imperial Innovations Limited | Asymmetric membranes for use in nanofiltration |
US10328396B2 (en) | 2010-07-19 | 2019-06-25 | Ip2Ipo Innovations Limited | Asymmetric membranes for use in nanofiltration |
US20230024915A1 (en) * | 2021-07-16 | 2023-01-26 | Battelle Memorial Institute | Porous Polybenzimidazole Membrane Supports for Composite Membranes |
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